Propeller



Mm N 1+ I Zmventor PROPELLER c. H. HAVILL Filed Nov. 25, 1929 km 7 m4 May 10, 1932.

Patented May 10, 1932 UNITED STATES PATENT OFFICE CLINTON H. HAVILL, OF ORANGE, NEW JERSEY, ASSIGNOB TO THE AMERICAN PRO- PELLER COMPANY, 01 BALTIMORE, MARYLAND, A CORPORATION OF MARYLAND raornLLnn Application nun November as, 1929. Serial in. 400,700.

I5 apertured, hollow blades, rotation of the latter producing a partial vacuum in the exhaust line whereby the mean effective pressure of the engine is increased with a result-' ant increase in efiiciency.

2 One of the objects of the present invention is to provide novel propelling means of the above type.

The temperature of the exhaust gases of an internal combustion engine is relatively high and in installations of the above character it is frequently desirable to prevent conduction or radiation of the heat in said gases to the shaft, which drivably carries the propeller hub, and also to the bearing members in which said shaft is rotatabl mounted, since these members are designe to operate -most efliciently at relatively low temperatures.

It is accordingly another object of the pres- 3 cut invention to provide novel means which are so constructed as to eliminate transfer of heat from engine exhaust gases passing through the .blades of a propeller to the propeller drive shaft assem 1y.

Another object of the invention is to provide, in an exhaust gas propeller, novel means carried by the hub for preventing the heated exhaust gases therein from directly contacting with the drive shaft.

A furtherobject is to provide a propeller of the above type wherein suitable heat insulation-is maintained in a novel manner between the exhaust gases and the propeller drive shaft.

A still further object is to provide in a hol- .present invention comprises a shaft 1 which low propeller adapted to discharge to the outside air the exhaust gases from an internal combustion engine, means to cause a positive circulation of cooling air adjacent the drive shaft.

Another object is to provide in a propeller of the above character an annular apertured baflle plate within the hub and concentrically arranged with respect to the drive shaft whereby during rotation of the latter cooling air will flow axially of the shaft and into the hub, due to the reduced pressure existing therein.

Still another object is to provide a novel propeller blade, for. use in apparatus of the above "character, provided with a plurality of slots adjacent the trailing edge thereof and disposed angularly with respect to the longitudinal axis of the blade.

*The above and other objects will appear more fully hereinafter in the following detailed description when taken in connection with the accompanying drawings. It is .to be expressly understood, however, that the drawings are for purposes of illustration only 75 and are not to be taken as a definition of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawings, wherein like reference characters refer to like parts throughout the severalviews,

Fig. 1 is a vertical section illustrating one embodiment of the present invention;

Fig. 2 is a plan v1ew of a portion of a propeller blade which may be used with the 35 structure shown in Fig. 1; and

Fig. 3 is an enlarged detail section of the trailin edge of the propeller blade ofFig. 2.

In t e form shown, the structure of the may be drivably connected to, or formed in tegrally with, the crankshaft of an internal combustion engine. Shaft 1 is rotatably supported as by means of a suitable bearing 2 in i a portion 3 of the engine frame and drivably carries at its outer end portion a hollow, propeller hub indicated generally at 4. The hub is preferably constituted by two coacting portions namely, a substantially semi-cylindrical front member 5 and a rear member 6 10 which, when assembled on shaft 1, securely maintain the roots 7 of the hollow blades 8, Fig. 2, in proper position. Suitable means are provided for securing the two portions of the hub together as will be understood by those skilled in the art.

Suitable means, not shown, may be provided for supplying lubricant under pressure to bearing 2 which lubricant is adapted to be stored in a reservoir 2 formed by an extension 3 of the engine frame 3. A packing member 3 is employed to prevent leakage of oil from the reservoir.

Means are provided for drivably connecting hub 4 to shaft 1, said means preferably being so constructed as to permit said hub to be readily removed from the shaft. In the form shown, the hub is driven from shaft 1 through the splined connection 9 and is securely held in place between front and rear cones 10 and 11 respectively, by means of a nut 12 threaded on the outer extremity of drive shaft 1. This nut forcescones l0 and 11 into intimate engagement with beveled faces 13 and 14 of the hub, a stop shoulder 15 being provided on the shaft in order to limit inward travel of the rear cone. If desired, a split expanding ring 16 may be fitted in an annular groove formed in hub portion 5 concentricall of shaft 1 in order to prevent any possi le outward movement of the hub after assembly thereof on the shaft.

Intercommunicating means are provided between the hollow hub and the exhaust manifold of one or more aircraft engines whereby the exhaust gases therefrom may be conducted through the hub and hollow blades to the atmosphere. In the form of the invention illustrated such means include a hollow annular member 17 which may be formed integrally with hub portion 6 and which telescopically fits within a stationary annular member 18 adapted to communicate with one or more exhaust pipes or manifolds 18 of one or more internal combustion engines. The hollow channel members 17 and 18 provide a closed passageway between the engine exhaust manifold and the hollow propeller hub for the flow of gases therethrough to the hollow blades.

In view of the difiiculty in providing a gastight seal between rotating and stationary members 17 and 18 respectively, these members are constructed in such a manner as to provide a slight clearance 19 therebetween.

uch clearance i insufiicient to permit any appreciable air leakage into the exhaust system and has the advantage of eliminating any friction which might exist between the members if a packing were employed.

In order that the exhaust gases may be conducted from the hub through the blades to the atmosphere, each of said blades is provided with a plurality of slots or openings 20, Figs. 2 and 3, which slots are arranged in the camber face and adjacent the trailing edge thereof. During rotation of the hub and blades, the exhaust gases therein tend to flow longitudinally of the blades due to centrifugal force, and in order that this direction of flow may be converted to a lateral flow without an abrupt change of direction, the slots 20 are angularly arranged with respect to the longitudinal axis of the blade, the inlet end of each slot beinglocated in a plane more closely adjacent the blade root than the discharge end thereof. By this arrangementthe direction of flow of the exhaust gases is gradually changed in an efiicient manner whereby losses in the kinetic energy of the gases and consequent changes in pressure thereof which might be caused by an abrupt change in the direction of flow are substantially eliminated. V

Slots 21 and 22 are provided adjacent the tip of each blade and are designed in such a manner as to provide an efficient means for permitting escape of solid or liquid particles which would be forced toward the outer end of the blade by centrifugal force. As shown,

slots 21 and 22 are preferably larger than slots 20.

Novel means are employed in the propeller hub for preventing the heat from the exhaust gases from being conducted to the shaft 1 and consequently to the bearing 2 which might cause binding and burning of the latter and such means are preferably so constructed as to cause a draft of cooling air to flow around said shaft during rotation of the propeller. In the form shown such means include an annular bafile plate 23, rotatable with the hub and arranged concentrically of shaft 1 but spaced therefrom to form an annular chamber 24. This chamber isada ted to communicate with the atmosphere t rough openings portion thereof, these openings being pro vided for a purpose which will appear more ,fully hereinafter. If desired a plurality of vanes 28, one adjacent each opening 25, may be mounted on the outer face of hub member 5, said vanes bein so arranged as to aid in forcing a flow of cooling air through chamber 24 during rotation of the propeller. It is pointed out that a sufficient number of openings 26 are arranged in the rear hub member 6 to permit a suflicient amount of air to be conducted therethrough whereby to eliminate any substantial amount of heat from being conducted from member 17 to the shaft 1 through cone 11.

In operation, shaft 1 upon being rotated will drive the hollow hub and blade assembly within which a reduction in pressure or partial vacuum will be created due to centrifugal force acting upon the mass of as or air therein. This will cause a rapid ow of exhaust gases from the engine or engines through the channel formed by members 17 and 18, the hollow hub and blades, to the atmosphere through slots 20, 21, 22. Because of the provision of openings 27 in member 23, chamber 24 communicates with the hollow hub, the partial vacuum maintained therein by rotation of the blades causing a positive flow of relatively cool air externally of the hub through said chamber and into the interior of the hub where said cooling air is mixed with the exhaust gases flowing therethrough.

There is thus provided by the present invention a' novel hollow propeller of the type wherein the exhaust gases from an internal combustion engine are conducted therethrough to the atmosphere, and wherein the passage of said gases through the propeller blades is accomglished in a simple and eflicient manner. y providing a plurality of angularly disposed slots in the propeller blades arranged in the camber face thereof and adjacent the trailing edge, the gases therein are exhausted to the atmosphere with minimum loss in kinetic energy and consequent change in the partial vacuum within the blades. By including the apertured bafile plate in the propeller hub, forming with the shaft a. chamber open to the atmosphere, a positive flow of cooling air axially of said shaft is maintained during rotation of the propeller, whereby said shaft is heat insulated from the hot exhaust gases in the hub, thus insuring cool and eflicient operation of the bearing or bearings in which said shaft is rotatably mounted. The present invention also provides a propeller which is constituted by a numer of separate parts which are easily assembled with respect to the shaft and which are readily removable therefrom.

While there-has beenillustrated and described one embodiment of the present invention, it is to be expressly understood that the same is not limited thereto, but may be embodied in various other forms which will now occur to those skilled in the art. For example the invention is applicable to geared propellers as well as direct-drive propellers. Reference will therefore be had to the appended claims for a definition of the limits of the invention.

What is claimed is: 1. In a propeller having a hollow hub adapted to communicate with the exhaust manifold of an engine, a lurality of hollow,

apertured blades carried y said hub, a shaft for driving said hub, a baflie late carried by said hub and surrounding said shaft, said baffle plate being spaced from said shaft to form a chamber, and means for establishing communication between the outside air and the chamber and between the latter and the interior of the hub whereby relatively cool air will be drawn through said chamber to 4 insulate said shaft fromthe heat of said exhaust gases during rotation of said shaft, hub and blades.

2. In a propeller of the type described, arotatable shaft, a hollow hub drivably connected therewith, a plurality of hollow blades carried by said hub, each of said blades having a plurality of openings therein, means for connecting the exhaust from an engine to said hub whereby exhaust gases from said engine will be conducted through said hub and blades during rotation thereof, and means for maintaining said shaft at a temperature lower than that of said gases comprising a baflie plate carried by said hub and arranged concentrically of said shaft and defining a chamber, said chamber being open to the outside air, and an opening in said bafiie late whereby communication between said 0 amber and hub is established to cause a flow of air through said chamber and into said hub.

3. In a propeller of the type described, a rotatable shaft, a hollow hub drivably connected with said shaft, a propeller blade operatively connected to said hub, said blade being provided with openings, means for conducting engine exhaust gases to said hollow hub, and means for causing a flow of cooling air axially of said shaft comprising an annular member carried by said hub and surrounding said shaft, said member being spaced from said shaft to form an annular chamber. an opening in said member, an opening in said hub, and a vane exterior of said hub and nected to said shaft, a. plurality of blades carried by said hub, each of said blades being hollow and having a plurality of angularlyarranged slots adjacent the trailing edge thereof, means for connecting said hollow hub to the exhaust of an engine whereby the exhaust gases therefrom willbe conducted through said hub and blades. and means for causing a flow of cooling air axially of said shaft and through said hub and blades.

5. In a propeller of the type described, a rotatable shaft, a hollow huh drivably carried by said shaft. a plurality of apertured hollow blades carried by said hub, means for leading the exhaust gases from an engine to said hub, and means for heat insulating said shaft from said exhaust gases comprising an apertured baffle plate surrounding and spaced from said shaft and defining a chamber. said chamber being open to the atmosphere to permit a flow of cooling air through said chamber and into said hub.

6. In an aeroplane propeller having in combination a rotatable shaft, a hollow hub connected to the exhaust of an engine, and a plurality of hollow blades carried by said hollow hub and communicating therewith, each of said blades being provided with a plurality of angularly disposed slots in the camber face adjacent the trailing ed e thereof whereby minimum resistance wi l he offered to the gases exhausted through the blade.

through said hollow blades whereby to insu-' late said shaft from the heat of said exhaust gases.

8. In an aeroplane propeller havin a hollow hub adapted to communicate with the exhaust of an engine, a shaft drivably connected to said hub, and a pluralityof lades carried by said hub each of said blades being provided with a plurality of slots arran ed in the camber face thereof and angularly isposed with respect to the longitudinal axis of the blade.

9. In a propeller of the type described, in combination, a hollow hub, a shaft for driving said hub, means for connecting said hollow hub with the exhaust of an engine, a plurality of hollow blades carried by and communicating with said hub, said blades being provided with openings, a baflle member within said hub and spaced from said shaft to form a chamber communicating with the outside air through openings in the hub, and means for causing, a flow of cooling air through said chamber including an opening in said member whereby communication between said chamber and hub will be established.

10. In combination with an aeroplane propeller having a rotatable hollow hub adapted to communicate with the exhaust of an engine, a plurality of propeller blades drivably connected to said hub, each ofsaid blades being hollow and communicating with said hollow hub, said blades being provided with a plurality of slots in the camber face adjacent the trailing edge and angularly disposed with respect to the longitudinal axis thereof, and openings adjacent the tip of each of said blades to permit escape of solid or liquid particles entrained in the exhaust gases.

11. A device of the class described comprising in combination, a shaft, means for 'rotatably supporting said shaft, a hollow hub drivably connected to said shaft, a plurality of hollow propeller blades carried by said hub said blades having openings therein,

means for conducting the exhaust gases from an engine to said hub while the latter is rotating and means for maintaining said shaft at aftemperature lower than that of the exhaust gases comprising an annular bafile plate within. said hub and defining therewith a chamber concentric of said shaft, said chamber communicating with the outside air and with the interior of the hub whereby a flow of relatively cool air is maintained therethrough during rotation of said shaft, hub and blades. I

12. In combination with an internal combustion engine of the type having an exhaust gas manifold and adapted to actuate a propeller shaft, a hollow propeller hub drivably connected to said shaft, hollow propeller blades having one or more openings therein connected to said hub, means for conducting exhaust gases from the manifold-to the hub whereb said gases may be exhausted to the atmosp iere through the opening or openings in said blades, a bafiie member in said hub, said bafile member being spaced from the shaft to provide an annular chamber thereabout, and means for forcing cooling air into the chamber and through the bafile plate into the propeller blade.

13. In combination With an internal combustion engine of the type having a crankshaft and an exhaust gas pipe, a hollow pro-' peller hub drivably mounted on an extension of said shaft, an apertured baffle plate positioned within the hub and laterally spaced from the crankshaft extension to provide a chamber about the latter, said chamber being open to the atmosphere through openings in said hub, hollow blades having openings therethrough, said blades being secured in said hub for rotation therewith, and means for continuously maintaining said hollow hub in communication with the exhaust pipe of the engine.

14. In apparatus of the class described, a

I hollow hub, and a hollow blade drivably connected to said hub for. rotation therewith, said 'blade being provided adjacent the trailing edge thereof with a plurality of inclined slots through which a fluid may be discharged, the discharge end of each of said slots being located at a point more distant from the hub than the inlet end of the slot. 7

15. In an aeroplane propeller, a hollow hub, and a hollow blade carried by said hub and rotatable therewith, said blade having an opening in the tip thereof closely adja- 'cent the trailing edge of the blade, said blade having a plurality of inclined slots in the camber face adjacent the trailing edge thereof with the discharge end of each of said slots located in a plane more distant from the hub than the inlet end thereof.

16. The method of cooling the hub portion of a propeller having a hollow hub and hollow blades through which a hot fluid is adaptaeeaeoe manifold and adapted to drive a propeller shaft, a two-part hollow hub secured to said propeller shaft for rotation therewith, said hub having diametrically disposed openings therein and being provided with an annular, hollow projecting member, means for securing the hub to said shaft, hollow blades having openings therein secured to the hub for rotation therewith, a stationary, hollow annular member in constant communication with said exhaust gas manifold and the hollow member projecting from the hub, and means carried by the hub for forcing cooling air into the same through certain of said hub openings.

18. In an aeroplane propeller, a hollow propeller hub having a centrally disposed opening, a propeller shaft projecting through said opening, means for securing said hub to said shaft, a plurality of apertured hollow blades mounted in said hub, a manifold member communicating :with said hollow hub and projecting laterally therefrom, a second manifold member stationarily mounted with. respect to the propeller hub and cooperating with said first named member to form a passage leading to said hollow hub, means cooperating with said second manifold member for conducting exhaust gases from an internal combustion engine into said passage for conduction through said hub and blades to the atmosphere, a plurality of openings formed in the forward portion of said hub for conducting air into said hub and blades, and means including a plurality of openings in the rear portion of said hub for efiecting amovable column of air through said hub and around said shaft for cooling the latter.

19. In a propeller of the type described, in combination, a hollow hub, a shaft for rotating said hub, said shaft extending through said hub, means for connecting the exhaust of an internal combustion engine with said hollow hub to conduct the exhaust gases thereto, a plurality of hollow blades carried by said hub,said blades being provided with openings adjacent the outer ends thereof, a member carried by said hub interiorly thereof and spaced from the shaft to form an annular chamber therearound, a plurality of openings in said hub adapted to establish communication between said chamber and the atmosphere forwardly and rearwardly of the hub, and means for establishing communication between the interior of the hub and the atmosphere for conducting atmospheric air through said hollow hub and blades with the exhaust gases during rotation of the propeller.

In testimony whereof I have signed this specification.

" CLINTON H. HAVILL. 

